What conditions are required for soft parts of an organism to become a fossil?
The process of a fossilisation, especially the preservation of soft parts, is a race against decay. When an organism dies, the cells begin a process of self-destruction. Chemicals called enzymes help recycle material within the cells of the living organism. However, when the organism dies, these enzymes go on the rampage and begin to break down the fabric of the cell – the organism literally begins to digest itself, a process called autolysis.
Scavengers and microbes– the recyclers
In addition to autolysis, the primary biological source of destruction for a dead organism is microbial decay. Dead organisms are a valuable nutrient resource and the activity of microbes recycles 90% or more of the organic matter in the environment (including dead organisms) before they are buried in the sediment. Scavenging organisms also contribute to the destruction of dead organisms. These feed on the flesh and in doing so, the hard parts may also be scattered, damaged or destroyed.
Physical damage can also destroy many biological remains. When an organism dies it may be transported, either by biological activity such as scavenging or trampling, or by physical factors such as waves, currents, tides, and wind. For dead organisms to become preserved there must be some special circumstances to reduce the degree of biological, chemical and physical activity, which usually destroys them. As will be explained later, these special circumstances range from early burial to lack of oxygen around the dead organism.
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